A visit from the federal government's top environmental protection chief Monday did not ease the concerns of Iowa agricultural leaders.

Andrew Wheeler, who last month took over as administrator of the U.S. Environmental Protection Agency, discussed myriad issues Monday in a meeting with top Iowa government and industry leaders at the State Fair.

The chief topic was the Renewable Fuel Standard, the federal requirement that a certain amount of corn-based ethanol be blended into the nation's fuel supply. Iowa leaders have expressed concern that various moves by President Donald Trump's administration has weakened the mandate, thus dampening the demand for ethanol and other biofuels.

Wheeler said earlier Monday in an interview with the bureau that the administration fully supports the letter and spirit of the mandate. But he also hedged on potential ways to preserve the mandate, leaving industry disappointed.

Under previous EPA administrator Scott Pruitt, the agency granted to some oil refineries waivers that allowed them to skirt the mandate.

Wheeler did not say the agency would cease the waiver process, only that he would provide more transparency to the waiver process.

"I know that's been a point of contention," Wheeler said during his interview with the bureau. "I want to provide more transparency about how we make those decisions."

Industry leaders have called for year-round access to E15, an ethanol blend that is only available during summer months, and for the agency to reallocate the millions of gallons that were lost as a result of previous agency actions.

Wheeler said the agency is "looking into" those proposals, saying he wants to be certain the agency has the legal authority to take such action.

He also indicated any approval of E15 for year-round access likely will be part of a package deal. Ag leaders say any concessions to the oil industry as part of any such deal will weaken the mandate.

Monte Shaw, executive director of the Iowa Renewable Fuels Association, said any such deal would not be greeted with approval from the renewable fuels industries.

Shaw was one of the industry leaders to meet with Wheeler at the State Fair.

"If you have a 15-billion (gallons mandated) RFS and every year you waive 1.5 billion gallons through the small refinery exemption, you really have a 13.5 billion (gallons mandated) RFS, which means you don't have an RFS for corn ethanol because we already blended in the low 14 (million gallons)," Shaw said.

Gov. Kim Reynolds, Iowa ag secretary Mike Naig, U.S. Rep. David Young and former Iowa Farm Bureau president Craig Lang also were among the dozens of government and industry leaders who attended the discussion with Wheeler.

Wheeler, in his interview with the bureau, said under his watch the agency will continue to examine ways to reduce regulations, and that a new rule regarding what small waterways are subject to federal regulations.

Ag groups pushed back against the rule under President Barack Obama's administration, saying it was too broad and subjected farmers to regulation of small collections of water on their farms. Environmental groups warn softening the rule will make it more difficult to observe and punish pollution.

"We want to provide certainty on what is a wetland to the American public so you know without going to court," Wheeler said.

Wheeler also said throughout his career he has been cognizant of costs associated with office expenses.

Pruitt resigned amid scrutiny of the agency's spending under his watch, among other allegations.

"I can't comment on any investigations," Wheeler said, "but I always have been, throughout my career, cognizant about costs. And that's continuing."

Wheeler said any expenses over a certain threshold must be approved my multiple individuals, and all travel expenses are "scrutinized."